Meeting Abstract
Brittle stars (Class Ophiuroidea, Phylum Echinodermata) have evolved a unique form of rapid, omnidirectional locomotion which requires them to coordinate their five arms and over 1,000 skeletal elements without a brain. When an arm is lost, they not only regenerate it, but function with near-equal locomotory facility using the remaining arms while the lost arm regrows. The control setup underlying this resilient, decentralized locomotion strategy is unclear, and has pertinent applications to the engineering of adaptive robots. The ophiuroid nervous system consists of a nerve ring at the center of the body that connects to a nerve that runs along the length of each arm. Suggested functions for the nerve ring range from a centralized processing unit to a simple connection between adjacent arms. We tested the function of the ophiuroid nerve ring through a series of experiments comparing locomotory behavior with and without intact nerve ring connections. The number and position of places where the nerve ring was severed were varied. Our observations show that the nerve ring connection is crucial for transmission of information between arms, but animals with breaks in the nerve ring continue to exhibit coordinated locomotion through shifts in the gait using the arms that remain connected. The next step for our research team is to test our hypothesized control setup through mathematical and robotic modeling, with the aim of informing the future design of resilient decentralized robots.
